The present invention relates to a refrigerating apparatus including a refrigerant circuit in which a refrigerant compressor, a water heat exchanger, a pressure reducing device and an evaporator are annularly connected by piping, and the refrigerating apparatus is configured to heat water supplied from a hot water storage tank and circulated through a water circuit by the water heat exchanger and to cool ambient water by the evaporator, thereby enabling cold storage.
Heretofore, as a method for cooling a cooling target such as food or beverage, a refrigerating apparatus using an evaporating compression type refrigerating cycle has broadly been utilized. In this type of refrigerating apparatus, the cooling target is cooled by a heat absorbing function by the evaporation of a refrigerant in an evaporator, and heat is radiated to the atmosphere by the heat radiation of the refrigerant in a radiator.
In recent years, in this type of refrigerating apparatus, attempts have been made to reuse the heat which has heretofore been released to the atmosphere and has not been utilized in the radiator (a heat exchanger), thereby effectively utilizing energy, and as one example of the attempts, an apparatus utilizing the heat radiated from the radiator (a water heat exchanger) for the supply of hot water has been developed.
Specifically, a high-temperature high-pressure refrigerant compressed by a compressor of the refrigerating cycle is caused to flow into the water heat exchanger, and in the water heat exchanger, heat exchange is performed between the refrigerant and water supplied from a hot water storage tank. By such heat exchange, the heat of the refrigerant is absorbed by the water discharged from the lower part of the hot water storage tank, whereby the heat is radiated.
On the other hand, the low temperature water discharged from the lower part of the hot water storage tank is heated by the heat exchange between the water and the refrigerant in this water heat exchanger, that is, the heat radiating function of the refrigerant, thereby obtaining the high temperature water (the hot water), and the water returns into the hot water storage tank through the upper part of the hot water storage tank. In this way, the low temperature water is discharged from the lower part of the hot water storage tank, and heated by the heat exchange between the water and the refrigerant flowing through the heat exchanger, and the high temperature water (the hot water) is returned into the hot water storage tank through the upper part thereof. When this operation is repeated, the high temperature hot water is stored from the upper part to the lower part of the hot water storage tank.
On the other hand, the refrigerant having the temperature lowered in the heat exchanger is contracted by an expansion valve, expands, has a low pressure, and then flows into the evaporator where the refrigerant expands, that is, evaporates. By the evaporating function of this refrigerant, the cooling target (e.g., the water) around the evaporator is cooled. Afterward, the refrigerant is discharged from the evaporator and sucked into the compressor again. By such a heat absorbing function of the refrigerant in the evaporator, the cooling target is cooled (e.g., when the cooling target is the water and the refrigerant is evaporated at 0° C. or less, ices are produced), and simultaneously by the heat radiating function of the refrigerant in the water heat exchanger, the high temperature hot water is produced (e.g., see JP-A-2007-78266 (Patent Document 1)).
In the above refrigerating apparatus, the operation of the refrigerating cycle is performed until the temperature of the cooling target cooled by the evaporator becomes a predetermined low temperature and the total amount of the water in the hot water storage tank is boiled (i.e., the hot water storage tank is full of the hot water). That is, even when the hot water storage tank is full of the hot water but when the cooling target is not sufficiently cooled, such a cooling operation is continued. In this case, however, the water supplied from the hot water storage tank and flowing through the heat exchanger is the sufficiently heated high temperature hot water, whereby the heat taken from the cooling target by the refrigerant in the evaporator cannot be released from the heat exchanger, which causes a problem that the refrigerating cycle is brought into an overloaded state.
On the other hand, even in a state in which the cooling target is sufficiently cooled, when the hot water storage tank is not full of the hot water, the cooling operation is continued. In this case, however, while flowing through the evaporator, the refrigerant cannot absorb the heat from the cooling target, and hence the water flowing through the heat exchanger cannot sufficiently be heated. Furthermore, the refrigerant cannot absorb the heat to evaporate in the evaporator, which might generate a liquid back flow, that is, the returning of a liquid refrigerant into the compressor.
The present invention has been developed to solve such problems of the conventional technology, and an object thereof is to provide a refrigerating apparatus which eliminates a disadvantage that a refrigerant circuit is overloaded and which can safely be operated.